Method of fabricating laboratory glassware

ABSTRACT

A method of fabricating laboratory glassware to provide a relatively small, rugged article of monolithic form having one or more relatively small fluid passageways therein which may be characterized as having the appearance of wormholes. The method includes the step of preforming sacrificial tubing, sections of which may be socketed together, and socketing the tubing with tubular connectors on assembly, prior to encapsulating the assembly in glass material. The sacrificial tubing is removed after encapsulation.

United States Patent 1 1 DeAngelis et al.

[ 1 Nov. 6, 1973 METHOD OF FABRICATING LABORATORY GLASSWARE [75] Inventors: William M. DeAngelis; Reinhardt F.

Luthmann, both of Wilton, Conn.; Charles A. Meehan, West Caldwell, N..l.; M. Howe Smith, Norwalk, Conn.

[73] Assignee: Technicon Instruments Corporation,

Tarrytown, NY.

221 Filed: Apr. 24, 1972 21 Appl; No.: 246,966

[52] U.S. Cl. "65/23 [Sl] lnt. Cl C03b 23/20 [58] Field of Search 65/23 [56] References Cited UNITED STATES PATENTS 2,l56,l56 Mahlck 65/23 X OTHER PUBLICATIONS A.P.C. Application Serial No.'l25,892, B. Wempe,

April 27, 1943, 2 pgs. spec, I sht. 'dwg.

Primary Examiner-Arthur D. Kellogg Att0rneyS. P. Tedesco [57] ABSTRACT A method of fabricating laboratory glassware to provide a relatively small, rugged article of monolithic form having one or more relatively small fluid passageways-therein which may be characterized as having the appearance of wormholes. The method includes the step of preforming sacrificial tubing, sections of which may be socketed together, and socketing the tubing with tubular connectors on assembly, prior to encapsulating the assembly in glass material. The sacrificial tubing is removed after encapsulation.

9 Claims, 5 Drawing Figures PATENTEDKDV 6 I975 SHEET 10F 2 PATENTEDnuv s 1915 SHEET 2 CF 2 METHOD OF FABRICATING LABORATORY GLASSWARE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method of fabricating laboratory glassware of monolithic form having one or more fluid passageways therein, provided with plural fluid connectors protruding therefrom and which have internal fluid junctions.

2. Prior Art Todays automated analysis equipment of the continuous-flow type employing multiple ducts for the passage of fluids including sample liquids, reagents and gases, and for splitting streams, combining streams and mixing stream, involve complex ductwork which must be precision-made to provide a smooth bore and a bore which has a closely controlled cross section. Moreover, in many instances the material in which the bore is formed must be inert so as to effectively resist corrosive attack. Heretofore, such ductwork has comprised fittings structured of glass tubing and constructed by a technique of lamp working. Such fittings have included junctions of diverse types having multiple inlets or outlets. These fittings have also included coils such as for the mixing therein of plural liquids or for the time delay of fluid flowing therein, the turns of which coils may be few or many depending on the extent of the mixing action required or depending on the extent of the time delay required in phasing of the flow through the coil,

with reference to fluid flowing in another passage. Such automated equipment is illustrated and described in Skeggs et al. U.S. Pat. No. 3,241,432 issued March 22, 1966.

As laboratories, such as hospital laboratories for ex-' ample, tend to become crowded with analytical equipment there is a need to reduce as far as practical the size of such automated analysis equipment. To this end, such ductwork may be miniaturized. While ductwork may be formed of exceedingly fine bore tubing, such as capillary tubing, this tubing is very subject to breakage as by impact with a foreign object or, more often, in the handling of fittings constructed of such capillary tubing. It is common practice to connect a fitting with a required section of flexible tubing by manually fitting a nipple-equipped section of tubing so that the nipple enters a bore of the fitting and forms a seal therewith.

Such manipulation often results in snapping of the fitting. Hence, there is a need for forming such ductwork in a small space and enclosed in a'glass block or slab, the whole'being very rugged and having protruding fluid connectors strongly resistant to snapping off as in the aforementioned manipulations, for example, required to couple such fluid connectors to sections of flexible tubing. So far as is known, at least it has not been practical heretofore to fabricate such ductwork, including junctions, monolithically.

It is known that heretofore an article of laboratory glassware such as a stopcock plug has been fabricated by molding the plug with a sacrificial tube or rod in such manner that the tube or rod is accessible after the molding operation. Thereafter, the sacrificial element may be removed by exerting a pulling force on the element so that its diameter is sufficiently reduced for the element to be withdrawn from the plug. Alternatively,

, the sacrificial element may be removed by an etching process. The resultant product has a bore therethrough for the passage of fluid. However, such a bore is a simple one, not requiring an internal junction. This fabrication technique is illustrated and described in Anastor U.S. Pat. No. 2,072,194 issued March 2, 1937.

It is also known that heretofore multiple electrical components, each having electrical leads, have been encapsulated in a monolithic structure with sacrificial tubing in suitable lengths and configurations interconnecting the desired ones of the electrical leads. After the encapsulating process, the sacrificial tubing is removed as with a suitable solvent, and the resultant bores are coated with a conductive material to provide the necessary electrical connections to the aforementioned leads which are left exposed in the bores after the removal of the tubing. This method of fabrication of a monolithic structure, illustrated and described in Corl U.S. Pat. NO. 3,233,310 issued Feb. 8, 1966, does not produce a product having an internal fluid junction.

. SUMMARY OF THE INVENTION One object of the invention is to provide a method of fabricating laboratory glassware of monolithic form having one or more fluid passageways therein, provided with plural fluid connectors protrudingtherefrom and which have internal fluid junctions.

Another object is to provide a method of fabricating an article having a fluid passageway in a glass material, which article has tubular connectors of a different material in communication with the passageway and extending without the glass material, utilizing tubing and tubular connectors of material having a higher melting point than the aforementioned glass material and an expansion coefficient compatible therewith. The method includes the step of preforming the tubing in accordance with a predetermined layout of passageway, with openings corresponding to the respective connections between the tubular connectors and the passageway; and assembling by socketing the preformed tubing with reference to the tubular connectors. The method ineludes the further steps of encapsulating the assembly in the glass material so as to permit access to at least the other end portions of the tubular connectors, utilizing heat; and removing the tubing to leave the passage way formed in the glass material with fluid connections to the tubular connectors held captive in the glass material.

DESCRIPTION OF THE DRAWINGS In-the drawings:

FIG. 1 is a perspective view of an article of laboratory glassware formed in accordance with the method of fabrication .of the invention;

FIG. 2 is an exploded view on a smaller scale of the assembly of parts in a mold-useful in theperformance' DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS There is shown in FIG. 1 a typical product of the method of fabrication embodying the invention, wherein a monolithic slab or block of glass is indicated at 10. The block, which is elongated, may have a relatively long length of approximately l inches or more or the block may have a length of 1% inches, for example. The size of the block will be largely dependent on the number, complexity, length and arrangement of the fluid passageways of circular cross section formed therein having only glass wall surfaces. One such fluid passageway in the block shown in FIG. 1 merely by way of example is a passageway 12 extending intermediate the ends of the block. This passageway has a vertical component, as in a curl portion 14. Though not shown, such a curl could well occur in a spiral portion of the passageway 12 according to the method of the invention as will be readily apparent hereinafter.

The passageway 12 has an inlet and an outlet formed by nipples l6 and 18 respectively, having fluid connections to the passageway 12 and held captive in the glass material so as to protrude therefrom in the manner shown to provide suitable coupling elements for fluid connections to conduits not shown The nipples 16, 18 constitute tubular connectors and these may be formed of a suitable inert metal such as platinum or they may be formed, for example, of sapphire material which, like platinum, has a higher melting point than glass and an expansion coefficient similar to that of glass.

As illustrated in FIG. 1, a similar tubular connector 20 extends from a distance above the block, where it is exposed, to a point inside the block where it has a junction with the passageway 12. Also, there is shown extending through one side of the block a similar tubular connector 212. An irregularly shaped passageway 24, having an exposed wall surface entirely of glass, interconnects the tubular connector or nipple 22 and the passageway 12.

The construction and arrangement of the tubular connectors and fluid passages 12 and 24 in the glass block are such that a stream of fluid, say a sample liquid, may be inletted through the tubular connector 16. A second fluid stream may join the fluid stream in passageway 12 through the junction between the passageway 24 and the passageway 12, the second stream, which may be a stream of a reagent liquid, being inletted to the tubular connector 22 having an internal junction with the inlet end of the passageway 24. A third fluid stream, say of another reagent may be inletted through the tubular connector to join the first and second fluid streams in the passageway 12, and these three liquid streams may be intermixed in the curl portion 14 of the passageway 12 before exit from the passageway 12 through the tubular connector 18.

FIGS. 2-5 illustrate articles which may be utilized in making the product of FIG. 1. ln FlG. 2 there is illustrated a box-like mold having a lower section 26, an upper section 28 and a floating top 30. The lower section 26 has 9 bottom and four upstanding'sides in the upper margin of three of which sides semicircular notches 32 are formed. The upper mold section 28 has corresponding sidewalls and has a vertical opening therethrough defined by the side walls. Three walls of the upper section 28, corresponding to those having the notches 32 therein, are provided in their lower margins with similar notches 34, only two of these notches being shown. The upper section 28 rests on the lower section 26 with the notches 34 in registry with the corresponding ones of the notches 32 when the mold is assembled. The floating top 30 of the mold, having a vertical hole 31 therethrough, is structured and dimensioned to fill only the upper portion of the vertical opening through the upper mold section 28 when the mold is assembled. The mold sections 26, 28 and 30 may be formed conveniently of carbon for nonadherence with the glass material.

As shown in FIG. 2, upper and lower plates 36, 38 are employed, these plates being preformed of a suitable glass material, such as borosilicate glass, to fit with slight clearance within the side walls-of the mold. The upper plate 36 has a vertical hole40 drilled therethrough which on assembly of the parts in the mold snugly receives the tubular connector 20 extending therethrough and which also extends with clearance through the hole 31 formed in the mold top 30.

Preformed sacrificial tubing of circular cross section, structured in accordance with a predetermined layout of the passageway 12 in the finished article of FIG. 1,

is indicated at 42 (FIGS. 2 and 4). This tubing, after forming, has a curl 43 in it corresponding to the curl portion 14 of the passageway 12. This tubing, having a thin wall structure, is sufficiently ductile to be bent into the desired shape but sufficiently rigid to retain its shaped configuration which may include a coil portion, for example, as previously indicated. The tubing 42 has an outer diameter closely approximating the diameter of the passageway 12. Also, such tubing, which may be formed of a metal alloy, is required to have a higher melting point than that of the glass material forming the I plates 36, 38 and have, in addition, an expansion coefficient compatible with such glass material. A metal alloy including nickel, cobalt and iron and sold under the trademark Kovar may be used for this purpose.

The tubing sections 42, having open ends for fluid communication with the tubular connectos l6 and 18, respectively, has holes 44 (FIGS. 4 and 5) formed in the side wall structure thereof in the proper location for fluid communication with the tubular connectors 20 and 22, respectively. The open ends of the tubing section 42 and the holes 44 of this section define sockets for the assembly of parts as will appear clearly hereinafter. In the illustrated form, the holes 44, which may be drilled, are of a diameter closely approximating that of the inner diameter of the last-mentioned tubular connectors.

Another section 46 of such sacrificial tubing is preformed in accordance with the predetermined layout of the passage 24 of FIG. 1 illustrating the final product. The tubing section 46 has an open end for a fluid outlet in communication with the hole 44 and an open inlet end for communication with the tubular connector 22. The tubing section 46 is illustrated merely by way of example as having an elbowed configuration after the preforming step, but it is to be understood that if desired the tubing section may have a helical configuration to form a spiral liquid mixing passageway or have some other configuration in accordance with a predetermined layout of a passageway in the final product. Also, it will be obvious that the tubing section 46 may have fluid connections, not shown, in addition to those illustrated and described, if desired. The fluid inlet end of the tubing section 46 defines a socket, the fluid outlet end of this section defining a part to be socketed, as will appear more fully hereinafter.

In the assembly of the aforementioned tubular parts as shown in FIGS. 2-5, the tubular connectors 16 and 18 are assembled to the tubing section 42 in like manner to the assembly of the tubular connector 22 with the inlet end of the tubing section 46 and hence description of the assembly of the latter will suffice. The tubular connector 22 is provided with an internal extension 48 which is received in the aforementioned socket defined by the fluid inlet end of the tubing section 46. In the illustrated form this extension 48 is formed as a separable tubular part or mandrel which is slidingly received in the connector 22 to extend within the last-mentioned socket, the extension member 48 constituting an alignment pin which extends entirely through the connector 22 as shown in FIG. 3. The ex tension 48, which may be formed of sacrificial tubing, has an outer diameter closely approximating the internal diameter of both the tubular connector'22 and the tubular section 46. The-manner of assembling the tubing section 46 with the tubing section 42 is shown in FIG. 4 and includes an extension member 50, similar to the member 48 but of shorter length, formed of sacrificial tubing and extending into both the open fluid outlet end of the tubing section 46 and into the socket hole 44 provided in the tubing section 42. The extension 50 bottoms against the cylindrical side wall structure of the tubing section 42 as shown in the last-mentioned view. Hence it will be understood that the tubing section 46 is socketed in the tubing section 42 on assembly of the parts.

The assembly of the tubular connector 20 with the tube section 42 is similar to that of the previously described assembly of the tubular connector 22 with the tubing section 46. However as shown in FIG. 5, the tubular connector 20 having an extension member 52 therein, similar, to the extension member 48 previously described, has the lower or outlet end thereof resting for support on the tubing section 42. The tubular connector 20 abuts the tubing section 42 as does the previously described fluid outlet end of the tubing section 46. Because in forming both the fluid connections of FIGS. 4 and 5 an internal extension is received within a socket, the corresponding ends'of both the tubular connector 20 and the tube section 46 may be squarely cut, instead of being cut to conform to the circular cross section of the tubing section 42. The extension member 52 bottoms against the circular cross section of the tube section 42 and the extension member 52 extends without thenipple 20 as shown in FIG. 2.

When the tube sections 42 and 46 are assembled with each other and with the corresponding ones of the tubular connectors 16, 18, 20 and 22 in the manner previously described, this assembly may be placed in the lower mold section 26 with the lower glass plate 36 below the assembly and supported on the bottom of the mold section. On this assembly with the mold section 26, the aforementioned tubular connectors 16, 18 and 22 are supported within corresponding ones of the notches 32 formed in this mold section. The upper glass plate 38 is placed on top of this assembly with tubular connector 20 extending through the aforementioned hole 40 in the plate 38 Prior to assembly of the upper glass plate 38, the upper mold section 28 is fitted in the aforementioned manner on the lower mold section 26. The assembly of the upper glass plate 38 is through the upper extremity of the vertical opening through the mold section 28. Thereafter, the floating top 30 of the mold is assembled to the upper mold section 28 with the tubular connector 20 extending through the hole 31 in the top. A suitable weight, not shown, is then placed on the top 30 to exert a light compressive force on the assembly within the mold. i

The weighted mold is then placed in a hightemperature furnace is an atmosphere of an inert gas to avoid oxidation and heated at approximately ],700 F for approximately 10 minutes, depending on the masses of the molds in the furnace and the furnace capacity. The mold is heated at this temperature only sufficiently long for the glass materia of the plates 36, 38 under compression as aforesaid, to flow sufficiently to encapsulate the aforementioned assembly in the mold. The glass material conforms to the wall structure of the mold and gases escape around the mold top 30. The glass material conforms closely to the tubing sections, the exposed portions of the tubular connectors and any exposed portions of the aforementioned extension members within the mold, such as the members 48 and 50 for example. Further heating at this temperature tends to result in crystallization of the glass material and should be avoided. The glass material may be annealed by being cooled to 400 F in a cool zone of the furnace, after which the mold is removed from the furnace. After cooling of the parts to handling temperature, the assembly is removed from the mold.

After the above-described encapsulation step, the extension members or alignment pins which protrude from the assembly may be removed by a pulling force from the respective tubular connectors 16, 18, 20 and 22. Thereafter an etchant, such as ferric chloride for example, may be pumped through the fluid passages in the assembly to remove the sacrificial tubing. In this removal step with reference to the sacrificial tubing, including the tubing section 42, 46 and extension member 50, the etchant may be inletted, say through the tubular connector 16, while the tubular connectors 20 and 22 are plugged temporarily, so that the etchant exits through the tubular connector 18. Subsequently, the etchant may be inletted in a similar manner, while the tubular connectors 18 and 22 are plugged, so as to exit from the tubular connector 20. In a similar manner, the etchant may be inletted as aforesaid, while the tubular connectors 18 and 20 are temporarily plugged, so that the etchant exits from the tubular connector 22. This removes all of the sacrificial tubingleaving the construction of FIG. 1. The article may'then be cleaned with water and such water may be pumped through the various passageways and tubular connectors associated therewith.

The finished product, having protruding tubular connectors, is very durable and not prone to breakage. The tubular connectors are so embedded in the glass mass that they very strongly resist breaking off. It is believed made clear that the internal passageways connected to the tubular connectors are formed entirely of exposed glass which is strongly resistant to corrosive attack. It will be obvious from the foregoing that intricate passageways may be formed in a block of slab of glass of monolithic form according to this method of fabrication, which intricate passageways may extend vertically as well as horizontally in the glass mass.

One advantage of the method of fabrication residing in the use of the socketed extension members 48, 50

and 52 is that these extension members ensure that during the encapsulation process the glass material does not flow between the tubular connectors and the corresponding sections of sacrificial tubing, nor between the sections 42, 46 of sacrificial tubing. The bores in the finished article are smooth and need not have restrictions therein such as would interfere with constant fluid flow rates through the bores. It will be evident that in the assembly of the tubular connectors with the sections of sacrificial tubing, the tubular connectors, instead of being socketed in the sacrificial tubing, may provide sockets to receive the sacrificial tubing.

While several forms of the invention have been described, it will be apparent to those versed in the art that the invention may take other forms and is susceptible of various changes without departing from the principles of the invention.

We claim: 1. A method of fabricating an article having a fluid passageway in a glass material which passageway has a junction therein, utilizing glass stock and elongated sections and sacrificial tubing of a material having a higher melting point that the glass material of the stock and an expansion coefficient compatible with said glass material, comprising the steps of:

preforming said tubing sections in accordance with a predetermined layout of said passageway;

positioning and supporting said preformed tubing sections with one another in accordance with said passageway layout, with one of said tubing sections having an end abutting another of said tubing sections intermediate the ends of the last mentioned section, at the location of said passageway junction;

covering at least the major portion of said tubing assembly with said glass stock;

molding said assembly in said glass material so as to permit access to said tubing sections, utilizing heat; and

removing said tubing sections by erosion to leave said passageway formed in said glass material.

2. A method as defined in claim 1 wherein: at least two of said tubing sections are socketed together by sliding an extension of one section of tubing into a socket formed by another section of tubing in the assembly of the parts.

3. The method as defined in claim 1, including removing said tubing with an etchant.

4. The method as defined in claimm 1, including removing said tubing by pumping an etchant therethrough.

5. A method as defined in claim 1, wherein: one of said tubing sections on preforming has an opening structured in the wall thereof intermediate the ends of the tubing section, and on assembling said tubing sections has the last-mentioned opening socketing an end of another tubing section at the location of said passageway junction.

6. The method as defined in claim 1-, wherein: said tubing sections are formed of metal, and said preforming of one of said tubing sections includes bending of the last-mentioned section in accordance with said predetermined layout of said passageway.

7. The method as defined in claim 6, wherein: said preforming by bending of said one tubing section includes imparting a curl thereto.

8. A method as defined in claim 1, wherein: a nipple' formed of erosion-resistant material is positioned and supported adjoining and in communication with one end of one of said tubing sections in the assembly of said tubing sections, said nipple extending without said glass material in the molding step and remaining captive in the glass material after said removal of said tubing sections.

9. A method as defined in claim 2, wherein: said two tubing sections are socketed together on assembly by an internal tubular mandrel of sacrificial material which extends between the last-mentioned tubing sections, which mandrel is removed by said erosion after said molding step. 

1. A method of fabricating an article having a fluid passageway in a glass material which passageway has a junction therein, utilizing glass stock and elongated sections and sacrificial tubing of a material having a higher melting point that the glass material of the stock and an expansion coefficient compatible with said glass material, comprising the steps of: preforming said tubing sections in accordance with a predetermined layout of said passageway; positioning and supporting said preformed tubing sections with one another in accordance with said passageway layout, with one of said tubing sections having an end abutting another of said tubing sections intermediate the ends of the last mentioned section, at the location of said passageway junction; covering at least the major portion of said tubing assembly with said glass stock; molding said assembly in said glass material so as to permit access to said tubing sections, utilizing heat; and removing said tubing sections by erosion to leave said passageway formed in said glass material.
 2. A method as defined in claim 1 wherein: at least two of said tubing sections are socketed together by sliding an extension of one section of tubing into a socket formed by another section of tubing in the assembly of the parts.
 3. The method as defined in claim 1, including removing said tubing with an etchant.
 4. The method as defined in claimm 1, including removing said tubing by pumping an etchant therethrough.
 5. A method as defined in claim 1, wherein: one of said tubing sections on preforming has an opening structured in the wall thereof intermediate the ends of the tubing section, and on assembling said tubing sections has the last-mentioned opening socketing an end of another tubing section at the location of said passageway junction.
 6. The method as defined in claim 1, wherein: said tubing sections are formed of metal, and said preforming of one of said tubing sections includes bending of the last-mentioned section in accordance with said predetermined layout of said passageway.
 7. The method as defined in claim 6, wherein: said preforming by bending of said one tubing section includes imparting a curl thereto.
 8. A method as defined in claim 1, wherein: a nipple formed of erosion-resistant material is positioned and supported adjoining and in communication with one end of one of said tubing sections in the assembly of said tubing sections, said nipple extending without said glass material in the molding step and remaining captive in the glass material after said removal of said tubing sections.
 9. A method as defined in claim 2, wherein: said two tubing sections are socketed together on assembly by an internal tubular mandrel of sacrificial material which extends between the last-mentioned tubing sections, which mandrel is removed by said erosion after said molding step. 